ru.linux

 
 - RU.LINUX ---------------------------------------------------------------------
 From : Sergey Lentsov                       2:4615/71.10   03 Mar 2002  15:38:04
 To : All
 Subject : URL: http://www.lwn.net/2002/0228/kernel.php3
 -------------------------------------------------------------------------------- 
 

    [1][LWN Logo] [No ads right now]
    [LWN.net]
 
    Sections:
     [2]Main page
     [3]Security
     Kernel
     [4]Distributions
     [5]Development
     [6]Commerce
     [7]Linux in the news
     [8]Announcements
     [9]Letters
    [10]All in one big page
 
    See also: [11]last week's Kernel page.
 
 Kernel development
 
    The current development kernel release is 2.5.5. Linus has released
    [12]the first 2.5.6 prepatch which contains a number of driver
    updates, the usual VFS work from Al Viro, an ALSA update, and a new
    scheme for process migration (see below).
 
    The latest prepatch from Dave Jones is [13]2.5.5-dj2; it is caught up
    with 2.5.6-pre1 and 2.4.19-pre1, and adds a number of other small
    fixes.
 
    The [14]February 27 version of Guillaume Boissiere's 2.5 Status
    document is available.
 
    The current stable kernel release is 2.4.18, which was [15]released on
    February 25. It was intended to be identical to the 2.4.18-rc4 release
    candidate; unfortunately, a slip of the fingers caused the one -rc4
    patch to be dropped from the final release. The result is that static
    applications on a few architectures will not work properly. There was
    a great deal of discussion on what should be done, but the consensus
    seems to be that the problem is not that severe. Thus there will not
    be a replacement 2.4.18 patch, or an expedited 2.4.19.
 
    The 2.4.19 process has begun with [16]2.4.19-pre1, which adds a rather
    larger set of fixes, but no real new features.
 
    Alan Cox has a couple of prepatches out there. [17]2.4.18-ac2 adds a
    small number of fixes to the 2.4.18 kernel. [18]2.4.19-pre1-ac2 brings
    in more stuff, including the USB 2.0 implementation and a number of
    hotplug support patches.
 
    On the 2.2 front, Alan has released [19]2.2.21-pre3 which adds another
    long set of fixes.
 
    Pressure to add new features to 2.4 is growing. Thus far, Marcelo has
    held a firm line with his 2.4 kernels: almost everything that goes in
    is a fix for some problem or other. As time goes by, however, there is
    an increasing number of requests for the merging new features and more
    intrusive changes. Recently there have been requests for new
    filesystems (XFS, JFS), [20]USB 2.0, the reverse mapping VM (Rik is
    not ready to see that merged yet, though he has [21]submitted the
    portion that shrinks struct page), the new scheduler, the [22]SD many
    patch, and more. The era of bugfix-only 2.4 releases may be coming to
    an end.
 
    This situation poses a bit of a challenge to Marcelo. If larger
    patches start to go into 2.4, chances are that new bugs will be
    introduced. Now that 2.4 is finally getting truly stable, few people
    would like to see it be destabilized again. On the other hand, the
    2.6/3.0 kernel could well still be two years away; it is unrealistic
    to expect that 2.4 will stand still for that long. If Marcelo does not
    release kernels with, at least, the more obvious and safe
    improvements, somebody else will.
 
    So expect the 2.4 releases to get more interesting. With luck and
    proper care, they hopefully won't get too interesting...
 
    The proper way to migrate processes. The new scheduler code in the 2.5
    series implements, among many other things, per-CPU run queues.
    Processes normally stay in the same queue, and run on the same
    processor; there are a number of performance benefits to doing things
    this way. Occasionally, however, it is necessary to move a process to
    another CPU; this move can happen as a result of load balancing
    (fixing a situation where one processor is switching between many
    tasks while another sits idle), or from an explicit user-space
    request.
 
    The 2.5.5 scheduler only allows the current process to be migrated to
    another CPU - essentially, processes must move themselves. This
    limitation gets in the way of a number of possible applications; it is
    often desirable to move arbitrary processes around as the result of
    user-space decisions. So a few people have been working on ways to
    relax the "current process only" constraint.
 
    Erich Focht [23]posted a patch which implements a "migration
    interrupt." When a process is to be moved, the target processor is
    interrupted; it waits until the process is in a movable state, then
    performs the required operations.
 
    The problem with this approach is that the target processor must wait
    in the interrupt handler for things to happen - never a good way to do
    things. If the target processor holds a resource (a spinlock, say)
    that the process to be moved requires, a deadlock could result. So
    Ingo Molnar has [24]posted a patch of his own which takes a different
    approach; this patch was included into the 2.5.6-pre1 prepatch.
 
    The new code works by setting up (yet another) kernel thread on each
    processor dedicated to the process migration task. When a process is
    to be moved, it is put onto a queue and the appropriate migration task
    is awakened. That task can wait for the process to become movable;
    since it is just running as another process, it can afford to wait as
    long as necessary (by giving up the CPU) without running the risk of
    deadlocks. It looks like a scheme that should work well, but expect a
    round of "what are those migration_CPU* processes?" questions after
    2.5.6 comes out.
 
    Doing the BK Thing, Penguin-Style. Jeff Garzik has [25]posted a
    document on how to do kernel development using BitKeeper. Since
    Linus's use of BitKeeper is increasingly looking like a permanent
    thing, this document is recommended reading for anybody who submits
    patches (even though use of BK is not required).
 
      On the developer's end, this also represents a fundamental
      disruption in the standard workflow of changes, commits, and
      merges. You will need to take a few minutes to think about how to
      best work under BitKeeper, and re-optimize things a bit. In some
      sense it is a bit radical, because it might described as tossing
      changes out into a maelstrom and having them them magically land at
      the right destination... but I'm getting ahead of myself.
 
    Have a look for the complete story.
 
    Other patches and updates released this week include:
 
    Core kernel code:
      * Michael Sinz has [26]posted a new version of his patch allowing
        the names of core dump files to be customized on a per-process
        basis.
      * Mike Kravetz has posted [27]a scheduler for NUMA systems which
        attempts to address the issues unique to that sort of platform.
        (The patch has since been [28]updated).
      * Erich Focht has [29]a NUMA patch of his own which takes a bit of a
        different approach.
      * Rik van Riel has released [30]version 12g of his reverse mapping
        VM implementation.
      * The [31]February 25 Linux security module patch is available.
        Among other things, it includes support for the [32]Linux
        Intrusion Detection System.
 
    Development tools:
      * Dan Aloni posted [33]an implementation of exceptions for the Linux
        kernel. The response has not been terribly positive...
      * [34]Syscalltrack 0.7 was released by Guy Keren.
      * Keith Owens has released [35]kdb v2.1 for the 2.4.18 kernel.
 
    Device drivers
      * David Miller and Jeff Garzik have [36]released a new Broadcom
        Tigon3 driver. "It is meant to replace Broadcom's driver because
        frankly their driver is junk and would never be accepted into the
        tree." (The latest version is [37]0.92).
 
    Filesystems:
      * [38]UVFS 0.5, a user-space filesystem implementation, was released
        by Britt Park.
 
    Miscellaneous:
      * Keith Owens has released [39]modutils 2.4.14.
 
    Networking:
      * [40]Version 0.93 of the Affix BlueTooth stack has been announced
        by Dmitry Kasatkin.
      * [41]Version 2.4.17-0.4.4 of the Linux SCTP implementation has ben
        announced by Jon Grimm.
      * The iptstate tool has been [42]released by Phil Dibowitz. "Based
        on the idea of IP Filter's 'statetop' feature, IP Tables State
        displays states in your firewall in a top-like format, in
        real-time."
 
    Ports:
      * James Bottomley has [43]updated his patch for the NCR Voyager
        architecture.
      * Robert Schwebel has [44]released a new version of his AMD Elan
        patch.
 
    Section Editor: [45]Jonathan Corbet
    February 28, 2002
 
    For other kernel news, see:
      * [46]Kernel traffic
      * [47]Kernel Newsflash
      * [48]Kernel Trap
      * [49]Linux 2.5.x Porting help
      * [50]2.5 Status
    
    Other resources:
      * [51]Kernel Source Reference
      * [52]L-K mailing list FAQ
      * [53]Linux-MM
      * [54]Linux Scalability Effort
      * [55]Kernel Newbies
      * [56]Linux Device Drivers
    
    
 
                                                   [57]Next: Distributions
 
    [58]Eklektix, Inc. Linux powered! Copyright Л 2002 [59]Eklektix, Inc.,
    all rights reserved
    Linux (R) is a registered trademark of Linus Torvalds
 
 References
 
    1. http://lwn.net/
    2. http://lwn.net/2002/0228/
    3. http://lwn.net/2002/0228/security.php3
    4. http://lwn.net/2002/0228/dists.php3
    5. http://lwn.net/2002/0228/devel.php3
    6. http://lwn.net/2002/0228/commerce.php3
    7. http://lwn.net/2002/0228/press.php3
    8. http://lwn.net/2002/0228/announce.php3
    9. http://lwn.net/2002/0228/letters.php3
   10. http://lwn.net/2002/0228/bigpage.php3
   11. http://lwn.net/2002/0221/kernel.php3
   12. http://lwn.net/2002/0228/a/2.5.6-pre1.php3
   13. http://lwn.net/2002/0228/a/2.5.5-dj2.php3
   14. http://lwn.net/2002/0228/a/2.5-status.php3
   15. http://lwn.net/2002/0228/a/2.4.18.php3
   16. http://lwn.net/2002/0228/a/2.4.19-pre1.php3
   17. http://lwn.net/2002/0228/a/2.4.18-ac2.php3
   18. http://lwn.net/2002/0228/a/2.4.19-pre1-ac2.php3
   19. http://lwn.net/2002/0228/a/2.2.21-pre3.php3
   20. http://lwn.net/2002/0228/a/usb-2.0.php3
   21. http://lwn.net/2002/0228/a/struct-page.php3
   22. http://lwn.net/2002/0228/a/sdmany.php3
   23. http://lwn.net/2002/0228/a/ef-scheduler.php3
   24. http://lwn.net/2002/0228/a/im-scheduler.php3
   25. http://lwn.net/2002/0228/a/bk-thing.php3
   26. http://lwn.net/2002/0228/a/coredump-name.php3
   27. http://lwn.net/2002/0228/a/mk-numa.php3
   28. http://lwn.net/2002/0228/a/mk-numa2.php3
   29. http://lwn.net/2002/0228/a/ef-numa.php3
   30. http://lwn.net/2002/0228/a/rmap.php3
   31. http://lwn.net/2002/0228/a/lsm.php3
   32. http://www.lids.org/
   33. http://lwn.net/2002/0228/a/exceptions.php3
   34. http://lwn.net/2002/0228/a/syscalltrack.php3
   35. http://lwn.net/2002/0228/a/kdb.php3
   36. http://lwn.net/2002/0228/a/tigon.php3
   37. http://lwn.net/2002/0228/a/tigon-0.92.php3
   38. http://lwn.net/2002/0228/a/uvfs.php3
   39. http://lwn.net/2002/0228/a/modutils.php3
   40. http://lwn.net/2002/0228/a/affix.php3
   41. http://lwn.net/2002/0228/a/sctp.php3
   42. http://lwn.net/2002/0228/a/iptstate.php3
   43. http://lwn.net/2002/0228/a/voyager.php3
   44. http://lwn.net/2002/0228/a/elan.php3
   45. mailto:lwn@lwn.net
   46. http://kt.zork.net/
   47. http://www.atnf.csiro.au/~rgooch/linux/docs/kernel-newsflash.html
   48. http://www.kerneltrap.com/
   49. http://www.osdl.org/archive/rddunlap/linux-port-25x.html
   50. http://kernelnewbies.org/status/
   51. http://lksr.org/
   52. http://www.tux.org/lkml/
   53. http://www.linux.eu.org/Linux-MM/
   54. http://lse.sourceforge.net/
   55. http://www.kernelnewbies.org/
   56. http://www.xml.com/ldd/chapter/book/index.html
   57. http://lwn.net/2002/0228/dists.php3
   58. http://www.eklektix.com/
   59. http://www.eklektix.com/
 
 --- ifmail v.2.14.os7-aks1
  * Origin: Unknown (2:4615/71.10@fidonet)
 
 

Вернуться к списку тем, сортированных по: возрастание даты  уменьшение даты  тема  автор